1. Field of the Invention
The present invention relates to a bond type flip-chip light-emitting structure and method of manufacturing the same, and in particular to a bond type flip-chip light-emitting structure, that is realized through a light-emitting-diode (LED) made by bonding a metal layer and a substrate into shape, to increase its contact area effectively, hereby increasing its heat dissipation capability.
2. The Prior Arts
In recent years, the light-emitting-diode (LED) has been considered one of the most promising Industries, mainly for its advantages of compact size, high efficiency, fast response, long service life, and not containing mercury hazardous to the environment, thus it is suitable for high power illumination.
However, the most important disadvantages of LED is its heat dissipation problem. To be more specific, when its light radiation efficiency is not good enough, such that the light that can not pass through and leave the light-emitting structure (the LED and its package) is turned into heat. In operation, in case the heat thus generated can not be led out of the light-emitting structure, then the temperature of the LED will certainly increase, to cause decrease of its reliability and performance.
For this reason, various heat dissipation solutions have been proposed for the light-emitting structure. Refer to FIG. 1 for a schematic diagram of the a flip-chip light-emitting structure of the prior art. As shown in FIG. 1, firstly, a GaN series LED 12 is grown on a sapphire substrate 10. Then a secondary transfer approach is used to remove the sapphire substrate 10 of inferior heat conductivity by means of laser irradiation or chemical etching. Subsequently, a silicon substrate 14 of better heat conductivity is bonded thereon to improve the heat dissipation capability of the LED. In the process mentioned above, flip-chip bonding is used to replace the conventional wire-bonding. The LED 12 thus produced includes: a first electrode 122, a second electrode 124, and a first weld-connection layer 126 and a second weld-connection layer 128 formed respectively on the first electrode 122 and the second electrode 124.
In the bonding process, the first weld-connection layer 126 and the second weld-connection layer 128 are bonded onto the corresponding first connection pad 142 and the second connection pad 144 on the silicon substrate 14 respectively.
In the structure mentioned above, in general, the weld-connection layer and connection pad are made of tin balls. As such, tin balls are fused to bond the LED 12 onto the silicon substrate 14. However, in this bonding and pressing process, the fused tin paste tends to exude out, and it can evenly overflow to the sidewall of LED 12, to cause short circuit of the p-n semiconductor layer in the LED 12, thus resulting in failure of the light-emitting structure. Moreover, in the flip chip process using the tin balls, the contact area between the LED chip and the substrate is rather small, so that heat can not be dissipated effectively. In addition, in this structure, area of negative electrode can not be reduced, so that the light emitting area is limited, hereby affecting its light-emitting efficiency. So, how to raise light emitting efficiency and heat dissipation efficiency is a problem that has to be solved urgently.
Therefore, presently, the design and performance of light-emitting structure of the prior art is not quite satisfactory, and it has much room for improvements.